I'm a bit late to the conversation but here's my opinion regarding game designs.
For me, H/porn games are neither porn nor game, it's both at the same time. I prefer my porn game to have a balance between gameplay and porn at the exact moment I play the game. It's a different experience than playing games for fun and watching porn to manage your libido, just for fun or any kind of personal enjoyment.
Although I doubt if there are actually people honestly watching porn just for fun and not doing anything else later? Maybe there are ... still ... doubtfully.
Playing porn games, for me, is to have fun with the design of both games and porn at the same time. it's like the best of both worlds, I can enjoy the game while getting soaked and I can manage it later.
If you take either of them from each other, such as lock entirely porn part as a reward and keep the game purely gameplay, or even separate the porn within gameplay to entirely other systems like [event scene only] or [collectible], etc. That's a no-go for me too as it just split [porn] part of the [game]. You best hope that the game itself is right to my taste and good enough so I can keep playing them as [game].
When I play porn games, my peak interest is in both topics, if either topic outshines another, then it's up to the quality of design for which one can interest me the most, if the game is boring, I'll just find a full save or workaround. If the porn is lackluster, hope the game is enjoyable enough for me to keep engaging them. And if both sucks, I'll just drop and find what best interests me elsewhere.
But I prefer my porn game to have obstacles and consequences involving them both in a balanced way, not intentionally failing to see the goods, not too overpowered to grind through the set, not too hideous of difficulty that keep me going nowhere, etc. The gallery is like an Omake(Extra material) more than a reward to me, they give a different feeling from encountering the goods directly from the game.
Although, as a customer, I can't always get the choice I wished, since dev has their own choices and vision too.
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Final thought
This is not to say that H/porn game cannot be enjoyable as a "game".
My personal choice is just this way regarding this genre of game.
If the game is good, having porn be an obstacle as a part of the game's design is even better!
It's entirely possible that H/porn game can be extremely enjoyable as a legit game that rivals any actual game without porn out there, be it AAA, indies or small-to-medium games. It's up to the developer's skills and design choice how good they can design them to be. For this game, I see it fine as it is too.
Some H-games I've played are really fun, some even make me forget about its porn part until I mess up or make a mistake, because their game design aspect is good, enjoyable, and right up my alley which is very few so far.
Some good H-game as a [game] for me as examples would be Bullet Requiem, Night of Revenge, Sailor Splendor, Koooonsoft's girls, Bioasshard, Mission Mermaiden and admittedly Malise and the Machine. There is more but that would be it for now.
That would be all. Have a good day!
